Using ePO should not affect the number of Microsoft Client Access Licenses (CALs) you need for Windows Server. But, you are advised to always review the terms of your Microsoft license and product use rights. McAfee Enterprise can't provide specific guidance on either of the following:

To help you make an assessment, know that ePO uses web server applications to communicate:

To make your assessment, you might find it helpful to look at Microsoft documents about general licensing policies, such as Microsoft Product List - Volume Licensing and Microsoft Product Use Rights. Both are available from: http://www.microsoft.com/licensing/products/products.aspx.